176504-00-0Relevant academic research and scientific papers
Synthesis and study of peptides with semirigid i and i+7 side-chain bridges designed for α-helix stabilization
Yu, Chongxi,Taylor, John W.
, p. 161 - 175 (2007/10/03)
A search for conformational constraints on the peptide α-helical conformation indicated that para-substituted amino acid derivatives of a benzene ring might be suitable for linking pairs of side chains that are separated by two turns of the helix. A 14-residue synthetic, amphiphilic α-helical peptide model system has been used to study the helix stabilizing effects of a series of four such bridges having constitutionally isomeric structures. These bridges were used to link positions 3 and 10 of the model peptides. The peptides were synthesized in good yield by standard solid-phase methods, including cyclization on the solid support. They were then studied for their solution conformations and melting behavior by circular dichroism (CD) spectropolarimetry, and for their elution behavior on reversed-phase HPLC columns. In aqueous solution and in 50% (v/v) trifluoroethanol, the most effective bridge for helix stabilization consisted of a 4-(aminomethyl)phenylacetic acid residue (AMPA) linked by amide bonds to the side chain functional groups of a (S)-2,3-diaminopropionic acid residue (Dap) in position 3 of the model peptide and an aspartic acid residue in position 10. This Dap3(AMPA), Asp10 bridge was about as effective as two Lys(i), Asp(i+4) lactam bridges incorporated linking residues 3 and 7, and 10 and 14, in the same model peptide sequence. This suggests that it is worth about 1kcal/mol of helix stabilization energy. Copyright (C) 1999 Elsevier Science Ltd.
A new strategy applied to the synthesis of an α-helical bicyclic peptide constrained by two overlapping i, i+7 side-chain bridges of novel design
Yu, Chongxi,Taylor, John W.
, p. 1731 - 1734 (2007/10/03)
A conformationally constrained, bicyclic, 14-residue peptide containing two overlapping i, i+7 side-chain bridges has been synthesized. The design of the side-chain linkage, which is built around a p-substituted benzene ring for rigidity, and the solid-phase approach applied to the peptide synthesis, are both new. A Boc/Benzyl peptide chain assembly method was combined with Fmoc/OFm orthogonal side-chain deprotection and solid-phase cyclization to form the first side-chain lactam bridge. A 2-(2-pyridyl)ethyl group (2-Pet), activated by methylation with CH3I in DMF, was then used in combination with Fmoc to allow a second orthogonal side-chain deprotection and solid-phase cyclization to form the second bridge. The circular dichroism spectrum of the product indicates that it is highly helical.
